A seat is an important equipment in people's daily life and work life. In order to make the seat more comfortable and convenient, many different kinds of adjustable seats are designed by people, such as folding seat, height-adjustable swivel seat, adjustable backrest tilt angle seat.
The existing multifunction seat generally is composed of the chassis, a handle, a backrest, a headrest and a cushion. Pursuing humanized work design, the chassis and the handle need to have multifunction operating structures. The backrest and the headrest are able to swing back and forth, and the cushion is able to slide back and forth so as to meet the expectations of comfort and ergonomic. In the existing design of seats, a plurality of handles are installed on both sides of the seat, but one handle has only one function. For example, one handle controls the height of the cushion, the other handle controls the backrest and the headrest to swing back and forth, yet another handle controls the cushion to slide back and forth. Obviously, there are so many handles that people feel more cumbersome when they use them. In addition, due to the limited space of the chassis, the structure of the multifunction chassis is usually bulky and heavy weight. Those control rods with various adjustment function are outwardly projecting. Not only much energy is wasted to move the seat, but also the appearance of the seat is ugly and the seat is difficult to operate. Therefore, a new structure of a seat has been proposed. The chassis is pivoted with the seat backrest frame, and then the seat backrest frame is pivoted by a sliding rod, so the backrest frame is able to swing relative to the chassis. The sliding rod is controlled by springs, which are controlled by an adjusting wheel. The slide block is mounted on the seat frame, and the movement of the cushion and the tilt angle of the backrest are controlled by a screw. For this kind of chassis, there still are some disadvantages, For example, the structure is complex and not easy to operate and the size is too big.
It is necessary to provide an improved adjustable seat to alleviate these defects.